Operating rooms have always included delivery systems for disinfectants, medications, and the like.
As operating equipment has become more sophisticated, the need for more sophisticated delivery systems has arisen.
Instruments such as endoscopes are at room temperature until they are inserted into the body cavity which is some 20 to 25 degrees warmer. This differential causes the lens to fog. One method of overcoming this problem is the use of a vial containing a defogging agent. This agent was disbursed on the endoscope by taking a syringe and inserting the same in the vial and removing the contents. Then the contents are dispersed on the end of the endoscope.
There are a number of problems with this approach to defogging surgical instruments. One of the main problems is that the defogging agent is withdrawn from the vial in the back of the operating room. The syringe is then passed to the sterile field where on numerous occasions the syringe has been mistaken for local anesthetic or medication containing syringes and then accidentally injected into the patient.
Additionally, it is difficult to hit the very small lens of the endoscope with the small stream of defogging agent. Further because of diseases such as hepatitis and AIDS, hospitals are trying not to use syringes whenever possible. Lastly, it is difficult to defog large masks or glasses with a small stream of defogging agent emitted from a syringe.
A second method of delivering defogging agents is the dropper bottle/sponge combination wherein the defogging agent is dropped either directly on the endoscope or on a sponge and then wiped on such endoscope. The longer the patient is undergoing surgery the greater risk of contamination of the sponge. It is also difficult to drop a droplet onto the small lens end of an endoscope. Further the dropper bottles are difficult to hold and manipulate. Finally, once the first drops are dispensed from the bottle, ambient air replaces the solution which contaminates such solution and it is no longer sterile which puts the patient at risk when further solution is dispensed from the dropper bottle.
Sterile wipes have also been used for applying defogging agents. The problem is that only one use per wipe can be made before disposing of the same because of contamination. Also these sterile wipes can not be used for defogging masks and glasses. Because these sterile wipes are a single use item, the cost of the same is extremely high.
Until now, the use of sterile aerosol technology has not been considered a viable delivery system for defogging agents for several reasons. First there are environmental issues associated with chloroflourocarbons CFCs which historically have been the only propellent available. Now with the phasing out of CFCs, it has not been considered economically feasible to develop alternate delivery systems for aerosol defogging agents. Also there are fears of using aerosols in operating rooms that have flammable solutions.